The invention relates to combustion engines and more particularly to fuel heating systems for internal combustion engines.
Vehicles with internal combustion engines such as transport trucks typically include a fuel tank supplying fuel to an engine by a fuel line. One or more fuel filters are positioned along the fuel line between the fuel tank and the engine to filter debris or contaminants from the fuel before the fuel enters the engine. Fuel filters of this nature are generally removable so they can be replaced at regular service intervals or when they become clogged. When operating in cold climates, fuel, and especially diesel fuel, has a tendency to thicken and become clogged in a fuel filter. This phenomenon is referred to as gelling of the fuel.
Currently, when diesel fuel gels in cold climates it clogs up the fuel filters when the vehicle either is off, at idle, or in operation and can prevent a vehicle from starting during a cold start or can quickly shut a vehicle down. For example, if a vehicle encounters a cold front while in operation, the fuel in the fuel filter may gel and prevent proper operation of the fuel system. Similarly, if a vehicle is started in a cold start condition, gelled fuel in the fuel filter may prevent the vehicle from properly starting. There are many variables to gelling of fuel, and water and wax clogging of the filter media in cold temperatures is one effect of gelling that starves the engine of fuel. The impact of this gelling process is a costly and time consuming endeavor including towing costs, downtime, replacement filters, service costs, and contractual penalties for delays placed on the shipping company for late deliveries.
Others have attempted to overcome the problem of gelling of fuel in fuel filters on vehicles by providing heating elements on the exterior of the fuel filter. For example, others have provided external wraps that apply to the exterior of a fuel filter housing. However, such external devices are often ineffective at solving the problems of preventing gelling because they do not provide adequate heat to the interior of the fuel filter to prevent gelling. Heating devices placed on the exterior of a fuel filter lose much of the applied heat outwardly to the ambient environment.
Another problem associated with fuel heating systems in vehicles includes reduction of fuel efficiency in various operating conditions. It has been observed through research that when a vehicle engine is first started, especially during the first two to four hours of operation, the fuel economy achieved is lower than the fuel economy achieved after the fuel temperature reaches a higher level. Experimental observations also reveal that fuel temperature delivered to the engine in vehicles is generally not regulated. Additionally, the temperatures at which fuel is stored in underground tanks may vary significantly from ambient operating temperatures encountered during use. This leads to wide variance in incoming fuel temperatures delivered to the engine for combustion. It is observed that unregulated incoming fuel temperature may contribute to variance in fuel efficiency across diverse operating conditions.
What is needed, then are improvements in devices and methods for preventing gelling of fuel in fuel delivery systems, and also improvements in devices and methods for improving fuel efficiency.